1. Field of the Invention
The present invention generally relates to golf club heads, and more specifically to the heads of metal woods and drivers with an adjustable, pre-tension condition at the impact face area of the club head that can be adjusted and tuned to match the golf ball compression and decompression characteristics in relation to the particular golfer's swing.
1. Description of Related Art
This invention relates to the improvements in performance of golf clubs when used to propel a golf ball by a transfer of linear momentum during the impact phase between the golf club head and the golf ball.
The transfer of a momentum between a hard surface of an impacting mass and a resilient golf ball, involves a complex process that not only involves the velocity pattern of the golf club head during the transfer mechanism but also the deflection pattern of the golf ball under compression.
In addition, with the use of the traditional wooden headed clubs, a reverse shock wave is reflected from the back of the head which has a dimensioned shape configuration that focuses the reverse shock wave to the impact face in such a time frame so as to coincide with the expansion of the golf ball from its maximum compressed state. Thus, an additional acceleration factor can be added to the release velocity of the golf ball.
One good golf shot makes up for many bad shots. Several good shots keeps one addicted to the sport. Thus, manufacturers of golfing equipment have endeavored to satisfy consumer demand for better performing and more mistake tolerant golf clubs and balls. For drivers and fairway woods, which are made out of the traditional wooden headed clubs, it is known that a reverse shock wave is reflected from the back of the head to the face of the club. Thus, an optimally dimensioned and shaped golf club head configuration could focus the reverse shock wave to the impact face of the club at a frequency rate which coincides with compression and subsequent expansion of the golf ball from its compressed state. Thus, optimal coincidence between the transfer of the reverse shock wave to the golf ball and of the expansion from the compressed state of the golf ball adds a maximum amount of additional acceleration to the release velocity of the golf ball after impact. Therefore, the industry has long attempted to manufacture such an optimally shaped and dimensioned wooden headed configurations.
Therefore, manufacturers have developed golf club heads which notably increased the distance a ball would travel after being struck. However, while golf club head performance improved, skillful techniques or either a lucky swing is required to avoid either hooking or slicing the ball. Therefore, many amateur golfers will frequently play at least one mulligan per 18 holes to escape the score penalties for one bad tee-shot.
In response to consumer demand for mistake tolerant equipment, thin wall golf club heads made by investment casting technology were introduced. These thin wall golf club heads are known for having a much larger "sweet spot" on the face of the golf club. The "sweet spot", of course, is the area of the golf club face which must strike the ball to yield a long and accurate shot. Because thin wall golf club heads have a cavity within the head, the reverse shock wave phenomena of the wooden heads is replaced by the deflection and subsequent return motion of the golf club face. Thus, the thin wall golf club heads have been manufactured to attempt to match the golf ball compression and expansion characteristics so as to achieve the effect of adding additional acceleration to the release velocity of the golf ball upon impact.
The introduction of thin wall golf club heads by the use of investment casting technology, has substituted the reverse shock wave phenomena by allowing the golf club face to deflect during golf ball compression during the first phase of impact. Thus, if the deflection and subsequent return motion have a time profile that matches the golf ball compression and expansion modes, then again there will be and additional acceleration phase applied to the release velocity of the golf ball.
However, it has been found that it is required to be extremely selective in the choice of the golf ball to be used with the so called "metal woods" in order to obtain the maximum performance possible. Moreover, with the tolerance used in the production of metal woods, the face thin-wall thickness can vary to the extent that the impact frequency characteristics can vary substantially between two apparently identical golf clubs made by the same manufacturer.
However, a problem with obtaining optimal deflection characteristics which match golf ball compression characteristics, is that the compression characteristics of the golf club head can vary substantially between two apparently identical golf clubs made by the same manufacturer. The reason for these variations is first a small difference in the thickness of the golf club face, a difference which is within tolerance, can have a large effect on the tension at the impact face area of the club head of the golf club and therefore its compression characteristics. Thus, a golfer must be extremely selective in the choice of his golf ball in order to obtain maximum performance possible. Indeed, different balls might be required to optimize the characteristic matching between the ball and the various fairway woods and driver. Unfortunately, the rules of golf do not allow ball substitution according to the club being used. Therefore, it is not realistically possible, to obtain maximum performance from a set of woods and driver with a given golf ball. This conclusion follows from the observation that, in all likelihood, each golf club will have a different deflection characteristic resulting from the production of the metal woods within known tolerances.
What is needed, therefore, is a golf club head design which allows the deflection characteristics to be fine-tuned and adjusted to match the golf ball compression characteristics for a given golf ball and a given golfer. The reason that the golfer fits into this equation, of course, is that the speed and energy of his or her swing affects the amplitude of the golf ball compression and, therefore, its compression characteristics.